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From:   Bartosz Golaszewski <brgl@bgdev.pl>
To:     Linus Walleij <linus.walleij@linaro.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Kent Gibson <warthog618@gmail.com>
Cc:     linux-gpio@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: [PATCH v2 1/9] lib: string_helpers: provide kfree_strarray()
Date:   Mon, 28 Sep 2020 12:41:47 +0200
Message-Id: <20200928104155.7385-2-brgl@bgdev.pl>
In-Reply-To: <20200928104155.7385-1-brgl@bgdev.pl>
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From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

There's a common pattern of dynamically allocating an array of char
pointers and then also dynamically allocating each string in this
array. Provide a helper for freeing such a string array with one call.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 include/linux/string_helpers.h |  2 ++
 lib/string_helpers.c           | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index 86f150c2a6b6..55b25120a1c6 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -94,4 +94,6 @@ char *kstrdup_quotable(const char *src, gfp_t gfp);
 char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp);
 char *kstrdup_quotable_file(struct file *file, gfp_t gfp);
 
+void kfree_strarray(char **str_array, size_t num_str);
+
 #endif
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 963050c0283e..bfa4c9f3ca0a 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -649,3 +649,28 @@ char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
 	return pathname;
 }
 EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
+
+/**
+ * kfree_strarray - free a number of dynamically allocated strings contained
+ *                  in an array and the array itself
+ *
+ * @str_array: Dynamically allocated array of strings to free. If NULL - the
+ *             function does nothing.
+ * @num_str: Number of strings (starting from the beginning of the array) to
+ *           free.
+ *
+ * Passing a non-null str_array and num_str == 0 as well as NULL str_array
+ * are valid use-cases.
+ */
+void kfree_strarray(char **str_array, size_t num_str)
+{
+	unsigned int i;
+
+	if (!str_array)
+		return;
+
+	for (i = 0; i < num_str; i++)
+		kfree(str_array[i]);
+	kfree(str_array);
+}
+EXPORT_SYMBOL_GPL(kfree_strarray);
-- 
2.26.1